What is a movement disorder?

A movement disorder can be defined as any disease or injury that interferes with a person's movement. By this definition, paralysis could be considered a movement disorder. However, movement disorders typically refer to conditions such as Parkinson's disease, essential tremor or tremor due to problems with a part of the brain called the cerebellum. For example, some patients with multiple sclerosis, which harms nerve fibers in the brain, will have severe tremor.

What are these conditions?

Parkinson's Disease
Parkinson's disease is a common disorder affecting nearly three out of one hundred persons over the age of 65 years. It is becoming increasingly diagnosed in younger persons under the age of 50 years.
Parkinson's disease is caused by degeneration of brain cells that make a chemical called dopamine. When these cells degenerate, the patient runs out of dopamine and develops slowing of movement, difficulty with speech, slowed and shuffling walking and tremor. Parkinson's disease is often very difficult to diagnose because not every patient has all the same symptoms.

Essential Tremor
Essential tremor is a common movement disorder that usually affects the head, chin, outstretched hands or voice. This disease causes tremor that is disabling in some. The cause of essential tremor is unknown, although it does run in some families.

Multiple Sclerosis
Multiple sclerosis is another common disease and tends to begin in young adulthood. Multiple sclerosis can affect any part of the central nervous system. When it affects the cerebellum or the cerebellum's connections to other parts of the brain, severe tremor can result.